CRM-12597

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* CRM-12597: CLONE - Undefined variable: val in CRM_Contribute_BAO_Query::whereClauseSingle()
  http://issues.civicrm.org/jira/browse/CRM-12597
CRM-12597

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* CRM-12597: CLONE - Undefined variable: val in CRM_Contribute_BAO_Query::whereClauseSingle()
  http://issues.civicrm.org/jira/browse/CRM-12597
Merge pull request #722 from dlobo/CRM-12597

CRM-12597 - Handle changed / unknown fields in a better way